diff --git a/dlls/mmsystem.dll16/mmsystem.c b/dlls/mmsystem.dll16/mmsystem.c
index b07629bd7b..94bb85faf6 100644
--- a/dlls/mmsystem.dll16/mmsystem.c
+++ b/dlls/mmsystem.dll16/mmsystem.c
@@ -108,7 +108,7 @@ void MMSYSTEM_MMTIME32to16(LPMMTIME16 mmt16, const MMTIME* mmt32)
  *
  *
  */
-void MMSYSTEM_MMTIME16to32(LPMMTIME mmt32, const MMTIME16* mmt16)
+static void MMSYSTEM_MMTIME16to32(LPMMTIME mmt32, const MMTIME16* mmt16)
 {
     mmt32->wType = mmt16->wType;
     /* layout of rest is the same for 32/16,
diff --git a/dlls/mmsystem.dll16/winemm16.h b/dlls/mmsystem.dll16/winemm16.h
index 2435e90807..e8cad537d8 100644
--- a/dlls/mmsystem.dll16/winemm16.h
+++ b/dlls/mmsystem.dll16/winemm16.h
@@ -24,7 +24,6 @@
 
 /* mmsystem (16 bit files) only functions */
 void            MMDRV_Init16(void);
-void 		MMSYSTEM_MMTIME16to32(LPMMTIME mmt32, const MMTIME16* mmt16);
 void 		MMSYSTEM_MMTIME32to16(LPMMTIME16 mmt16, const MMTIME* mmt32);
 
 typedef LONG			(*MCIPROC16)(DWORD, HDRVR16, WORD, DWORD, DWORD);